Pyrolysis/Gasification System For use in a Method of Carbon Sequestration

ABSTRACT

The present invention provides a nitrogen oxide ultra-low emission and carbon negative emission system and a control method, and the system comprises: a carbon negative emission system, a nitrogen oxide ultra-low emission system, an air supply device and a flow control module. The carbon negative emission system is used for enabling biomass to produce inorganic carbon and pyrolysis gas/gasification gas to realize negative emission of carbon; the nitrogen oxide ultra-low emission system is used for enabling fuel to be in mixed combustion with the pyrolysis gas/gasification gas to remove nitrogen oxides, which realizes ultra-low emission of the nitrogen oxides; the air supply device is in communication with biomass pyrolysis coupling partial gasification via a first pipeline, the air supply device is in communication with the carbon negative emission system and the nitrogen oxide ultra-low emission system via a second pipeline, and the pyrolysis gas/gasification gas enters the nitrogen oxide ultra-low emission system via the second pipeline; the flow control module controls a flow ratio of a pyrolysis agent/gasification agent entering the carbon negative emission system and flow of the pyrolysis gas/gasification gas and air entering the nitrogen oxide ultra-low emission system.

TECHNICAL FIELD

The present invention relates to the technical field of energy savingand emission reduction, in particular to a biomass pyrolysis,gasification and combustion combined nitrogen oxide ultra-low emissionand carbon negative emission system and a control method.

BACKGROUND ART

In recent decades, environmental problems such as a greenhouse effect,glacier melting, acid rain and photochemical smog have become more andmore serious, and threaten the safety of human beings and ecosystems,which is closely related to the extensive use of coal-based fossil fuel.

Biomass is a kind of renewable energy, it achieves zero emission ofcarbon and low emission of nitrogen oxides during its use due to itscarbon neutrality and low nitrogen characteristics, and the use of thebiomass to partially replace the fossil fuel can alleviate theenvironmental problems such as the greenhouse effect and acid rain to acertain extent.

Although the use of the biomass has already achieved zero carbonemissions and low nitrogen combustion, it still faces great challengesto achieve the strategic goals of carbon neutralization, carbon peakingand ultra-low emission of nitrogen oxides.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides a nitrogenoxide ultra-low emission and carbon negative emission system and acontrol method, and ultra-low emission of nitrogen oxides and carbonnegative emission are achieved by an integrated system combining biomasspyrolysis, gasification and combustion and a control method.

The present invention provides a nitrogen oxide ultra-low emission andcarbon negative emission system, comprising: a carbon negative emissionsystem, a nitrogen oxide ultra-low emission system, an air supply deviceand a flow control module, wherein

the carbon negative emission system is used for enabling biomass to havea pyrolysis coupling partial gasification reaction or enabling thebiomass to have a pure pyrolysis reaction to generate inorganic carbonand pyrolysis gas/gasification gas; the inorganic carbon is used forreturning to field treatment or making carbon-based materials such asactivated carbon to realize negative emission of carbon;

the nitrogen oxide ultra-low emission system enables fuel to be in mixedcombustion with the pyrolysis gas/gasification gas to remove nitrogenoxides generated by combustion of the fuel;

the air supply device is in communication with the carbon negativeemission system via a first pipeline, and provides a pyrolysisagent/gasification agent required for biomass pyrolysis coupling partialgasification, the air supply device is in communication with the carbonnegative emission system and the nitrogen oxide ultra-low emissionsystem via a second pipeline, and the pyrolysis gas/gasification gasenters the nitrogen oxide ultra-low emission system via the secondpipeline, and is in mixed combustion with the fuel in the nitrogen oxideultra-low emission system to reduce the nitrogen oxide, so as to achieveultra-low emission of the nitrogen oxide;

the flow control module controls a flow ratio of the pyrolysisagent/gasification agent entering the carbon negative emission systemand flow of the pyrolysis gas/gasification gas and air entering thenitrogen oxide ultra-low emission system.

According to the technical solution, the biomass generates the inorganiccarbon and the reductive biomass pyrolysis gas/gasification gas throughpyrolysis coupling partial gasification, the inorganic carbon can beused for returning to field treatment and soil improvement, since theinorganic carbon is difficult to be decomposed by soil microorganisms,this part of carbon can be sealed for a long time by performingreturning to field treatment on it, and this part of carbon just comesfrom carbon dioxide in atmosphere fixed by the biomass, and finallynegative emission of carbon is achieved. The inorganic carbon can alsobe used to make the carbon-based materials such as activated carbonadsorbents to adsorb harmful substances and accumulate and store them toachieve negative emission of carbon; the reductive biomass pyrolysisgas/gasification gas co-fires with biomass/coal solid fuel in thenitrogen oxide ultra-low emission realization system, and the nitrogenoxides are converted into nitrogen that is harmless to the environmentthrough complex chemical reactions, and the removal rate of the nitrogenoxides can be as high as 80%, which realizes removal of the nitrogenoxide and achieves the purpose of ultra-low emission of the nitrogenoxide. The present invention regulates and controls the yield of thegasification gas/gasification gas and the component ratio, regulates andcontrols the yield of the inorganic carbon, and realizes the removal ofthe nitrogen oxide and the negative emission of carbon in the process ofbiomass utilization by combining biomass pyrolysis, gasification andcombustion, and controlling the flow of flue gas entering the carbonnegative emission system and the flow ratio of the pyrolysisagent/gasification agent provided by the air supply device.

In an optional technical solution of the present invention, the carbonnegative emission system comprises a dryer, a pyrolysis coupling partialgasification reaction furnace and a first cyclone separator which aresequentially in communication via pipelines, the dryer dries the biomassprovided, the dried biomass enters the pyrolysis coupling partialgasification reaction furnace via a second outlet of the dryer to havethe pyrolysis coupling partial gasification reaction or the purepyrolysis reaction, and the product after the reaction of the biomassenters the first cyclone separator via an outlet of the pyrolysiscoupling partial gasification reaction furnace to perform gas-solidseparation.

According to the technical solution, drying the biomass beforepyrolysis/gasification of the biomass is beneficial to improve theefficiency of pyrolysis/gasification of the biomass, combustion productsare separated by the first cyclone separator, and the reductivepyrolysis gas/gasification gas obtained by separation enters thenitrogen oxide ultra-low emission system to reduce the nitrogen oxide,the combustion products are separated, so that full recovery of theinorganic carbon can be promoted, at the same time the entry of fineinorganic carbon in the combustion products into the nitrogen oxideultra-low emission system is reduced, and the negative emission ofcarbon is promoted.

In an optional technical solution of the present invention, thepyrolysis coupling partial gasification reaction furnace comprises areaction furnace body, a reaction furnace shell, an inorganic carbonchamber, an inorganic carbon emission port and a pyrolysisagent/gasification agent air port, the reaction furnace body is disposedinside the reaction furnace shell, a circulation space of the pyrolysisagent/gasification agent is formed between the reaction furnace shelland the reaction furnace body, the reaction furnace shell is incommunication with an outlet of the first pipeline, the inorganic carbonchamber is disposed at a bottom of the pyrolysis coupling partialgasification reaction furnace, a bottom of the inorganic carbon chamberis provided with the inorganic carbon emission port, and the pyrolysisagent/gasification agent air port is formed in the reaction furnacebody.

According to this technical solution, the reaction furnace body is usedfor the pyrolysis coupling partial gasification reaction to take place,the reaction furnace shell is in communication with an outlet of thefirst pipeline, and the pyrolysis agent/gasification agent provided bythe air supply device enters the reaction furnace shell to provide gasand heat required for the reaction furnace body, and the pyrolysisagent/gasification agent in the reaction furnace shell enters thereaction furnace body through the pyrolysis agent/gasification agent airport to enable the biomass to have the pyrolysis coupling partialgasification reaction. According to different pyrolysisagents/gasification agents, the pure pyrolysis reaction can also takeplace in the reaction furnace body, for example, the pyrolysisagent/gasification agent is nitrogen, and the inorganic carbon in thecombustion products generated in the reaction furnace body enters theinorganic carbon chamber and passes through the inorganic carbonemission port to be discharged, which realizes recovery of the inorganiccarbon. The inorganic carbon can be used for returning to fieldtreatment and soil improvement. Since the inorganic carbon is difficultto be decomposed by the soil microorganisms, this part of carbon can besealed for a long time, and finally negative emission of carbon isachieved. The inorganic carbon can also be used to make the carbon-basedmaterials such as activated carbon adsorbents, which can adsorb harmfulsubstances and accumulate and store them to achieve negative emission ofcarbon.

In an optional technical solution of the present invention, the nitrogenoxide ultra-low emission system comprises a boiler and air supplymechanisms, the boiler is used for combustion of the fuel and thepyrolysis gas/gasification gas, the air supply mechanisms provide gasrequired for the combustion of the fuel, and the boiler is incommunication with a top outlet of the first cyclone separator throughthe second pipeline.

According to this technical solution, combustion of the fuel in theboiler can provide heat to the outside, and the reductive pyrolysisgas/gasification gas obtained by separation of the first cycloneseparator enters the boiler through the second pipeline to reduce thenitrogen oxides in the boiler to nitrogen, which achieves ultra-lowemission of the nitrogen oxide.

In an optional technical solution of the present invention, the airsupply mechanisms comprise a first air supply mechanism and a second airsupply mechanism, the first air supply mechanism is disposed at thebottom of the boiler, and the second air supply mechanism is disposedcorresponding to a combustion zone of the pyrolysis gas/gasification gasin the boiler.

According to this technical solution, the second air supply mechanism isdisposed corresponding to the combustion zone of the biomass pyrolysisgas/gasification gas, and by additionally disposing a secondary air portin the combustion zone of the biomass pyrolysis gas/gasification gas, onthe premise that it is guaranteed that the total air supply volumeremains unchanged, the air volume of primary air is reduced, and reducedair is supplied into a hearth in the form of secondary air. When theprimary air volume decreases, the combustion condition of the biomasssolid fuel in a dense phase zone will change, the nitrogen oxide ispartially removed in the dense phase zone, and the total removalefficiency of the nitrogen oxide is improved.

In an optional technical solution of the present invention, a fuel feedbin and an oxygen meter are further included, the fuel feed bin providesthe fuel required for the combustion of the boiler, the number of thefuel feed bins is one or more, the oxygen meter is disposedcorresponding to the combustion zone of the pyrolysis gas/gasificationgas in the boiler, and the oxygen meter is used for monitoring thecontent of oxygen in the combustion zone of the pyrolysisgas/gasification gas.

According to this technical solution, the plurality of fuel feed binscan provide different fuels respectively. The fuel can be pure biomassfuel or pure coal fuel, or a mixture of biomass fuel and coal fuel. Theoxygen meter ensures the ultra-low emission of the nitrogen oxide bymonitoring the content of the oxygen in the combustion zone of thepyrolysis gas/gasification gas and the excess air coefficient, andadaptively adjusting the air supply volume of the air supply mechanism.

In an optional technical solution of the present invention, the airsupply device comprises an air blower and a combustion chamber, the airblower is used for blowing in air/nitrogen, the air blower provides thepyrolysis agent/gasification agent (nitrogen/air) required for thecarbon negative emission system, an outlet pipeline of the air blower isin communication with an inlet of the first pipeline, the combustionchamber is in communication with a second inlet of the dryer via a thirdpipeline, the combustion chamber is used for combustion of part of thepyrolysis gas/gasification gas, and the combustion chamber is incommunication with a middle part of the second pipeline via a fourthpipeline, and the first cyclone separator is in communication with theboiler via the second pipeline; flue gas generated by combustion in thecombustion chamber enters the dryer through the third pipeline andprovides heat for drying the biomass in the dryer, and after drying,this part of flue gas enters the first pipeline together with watervapor precipitated in the drying process of the biomass fuel.

According to this technical solution, gas blown in by the air blower isdifferent, and reactions happening to the biomass carbon negativeemission system are different. When air is blown in, the pyrolysiscoupling partial gasification reaction occurs in the pyrolysis couplingpartial gasification reaction furnace, the increase of a ratio of an airgasification agent will increase the content of CO and CH₄ in agasification product and the heating value of the gasification gas, butwill reduce the content of H₂; when nitrogen is blown in, the purepyrolysis reaction occurs in the pyrolysis coupling partial gasificationreaction furnace, the content of reductive gas in the gas product,especially the content of H₂ and CO, will be greatly reduced, but thecontent of the inorganic carbon will be increased to some extent. In thecase where the pyrolysis gas with a low H₂ and CO content can stillachieve high denitrification efficiency, by controlling to only have thepyrolysis reaction in the pyrolysis coupling partial gasificationreaction furnace, the yield of the inorganic carbon is increased whileensuring high denitrification efficiency, which achieves negativeemission of carbon to a greater extent. The combustion chamber is incommunication with the dryer to provide heat for drying the biomass. Inan optional technical solution of the present invention, an induceddraft fan and a gas component analyzer are further included, the induceddraft fan and the component analyzer are disposed on the secondpipeline, the induced draft fan is disposed at an inlet of the secondpipeline, and the gas component analyzer is disposed at an outlet of thesecond pipeline. The induced draft fan is disposed, which is beneficialto rapidly introduce the biomass pyrolysis gas/gasification gasseparated by the first cyclone separator into the boiler, and the gascomponent analyzer is used to analyze the component and content of thebiomass pyrolysis gas/gasification gas entering the boiler.

In an optional technical solution of the present invention, the airsupply device further comprises a first outlet pipeline and a watervapor generator, and the inlet of the first pipeline is in communicationwith a first outlet of the dryer via the first outlet pipeline; the fluegas generated by combustion in the combustion chamber is provided forthe pyrolysis coupling partial gasification reaction furnace via thefirst outlet pipeline together with the water vapor precipitated whendrying the biomass fuel as the pyrolysis agent/gasification agent; anoutlet pipeline of the water vapor generator is in communication withthe inlet of the first pipeline, and the water vapor generator providesthe pyrolysis agent/gasification agent required for the pyrolysiscoupling partial gasification reaction furnace.

According to this technical solution, the flue gas generated by thecombustion of a small part of the pyrolysis gas/gasification gas in thecombustion chamber is beneficial to provide heat for the pyrolysiscoupling partial gasification reaction, and the increase in theproportion of a water vapor gasification agent will increase the contentof H₂ in the gasification product, however, it will reduce the contentof CO and CH₄, and also reduce the heating value of the gasificationgas. By reasonably controlling the content of the water vaporgasification agent and the air gasification agent, the gasificationproduct has both extremely high denitrification efficiency and highheating value, so that energy can be fully utilized.

In an optional technical solution of the present invention, a pluralityof flow monitoring meters and a plurality of electric butterfly valvesare further included, the plurality of flow monitoring meters arerespectively disposed on the outlet pipeline of the air blower, theoutlet pipeline of the water vapor generator, the first outlet pipelineand an outlet of the second pipeline; the plurality of electricbutterfly valves comprise a first electric butterfly valve disposed onthe outlet pipeline of the air blower, a second electric butterfly valvedisposed on the outlet pipeline of the water vapor generator, a thirdelectric butterfly valve disposed on the fourth pipeline, and a fourthelectric butterfly valve disposed on the outlet of the second pipeline.

According to this technical solution, the ratio of the pyrolysisgas/gasification gas in the air blower, the water vapor generator andthe combustion chamber can be regulated and controlled by adjusting theopening degrees of the first, second and third electric butterflyvalves, and flow of each flow path can be monitored by the flowmonitoring meter, which can regulate and control the component and yieldof the biomass pyrolysis gas/gasification gas and the yield of theinorganic carbon, so as to achieve the purpose of optimal control overnitrogen oxide ultra-low emission.

The present invention further provides a control method of the nitrogenoxide ultra-low emission and carbon negative emission system, comprisingthe following steps:

when biomass in the carbon negative emission system has a pure pyrolysisreaction, closing the second electric butterfly valve and the thirdelectric butterfly valve; opening the first electric butterfly valve andintroducing nitrogen, and opening the fourth electric butterfly valve;or

when the biomass in the carbon negative emission system has a pyrolysiscoupling partial gasification reaction, opening the first electricbutterfly valve, the second electric butterfly valve, the third electricbutterfly valve and the fourth electric butterfly valve, the air blowerblowing in air;

adjusting a flow ratio of water vapor entering the carbon negativeemission system, air and fuel gas generated in the combustion chambertogether with water vapor precipitated when biomass fuel is dried bycontrolling the opening degrees of the first electric butterfly valve,the second electric butterfly valve and the third electric butterflyvalve, thereby adjusting a component ratio of pyrolysis gas/gasificationgas, the yield of the pyrolysis gas/gasification gas and the yield ofinorganic carbon.

In an optional technical solution of the present invention, furthercomprising controlling temperature of the boiler, an excess aircoefficient of the combustion zone of the pyrolysis gas/gasification gasin the boiler, a total excess air coefficient in the boiler, and adistribution ratio of air supply volumes of the first air supplymechanism and the second air supply mechanism to realize nitrogen oxideultra-low emission.

Through the present invention, the deficiencies in the prior art can besolved, in the prior art, a biomass pyrolysis and direct combustioncombined system, and a biomass gasification and direct combustioncombined system exist, and no pyrolysis, gasification and combustioncombined integrated system exists, and in the prior art, it focus on: 1.rationally opening and utilizing agricultural and forestry waste toprepare biochar; 2. overcoming the defect of coking on the heatingsurface, low boiler efficiency, large floor area, high maintaining costand the like in biomass direct combustion power generation; 3. solvingthe problems of tar blockage or pipeline corrosion or the like in theprocess of biomass pyrolysis; and 4. solving the problem of low heatload when biomass boilers burn crop straw in an existing bioenergy powergeneration system.

The goal of the present invention is to achieve negative emission ofcarbon by returning the inorganic carbon produced bypyrolysis/gasification to fields, and making the carbon-based materialssuch as activated carbon adsorbents, and achieves ultra-low emission ofthe nitrogen oxide by mixed combustion of high temperature fuel gas andhigh temperature tar generated by pyrolysis/pyrolysis coupling partialgasification, and solid biomass/coal/biomass and coal mixed solid fuel;and at the same time, by controlling the flow ratio, reactiontemperature, excess air coefficient, and primary and secondary air ratioof the different pyrolysis agent/gasification agent (high-temperatureflue gas produced by the combustion of the water vapor, theair/nitrogen, and the pyrolysis gas/gasification gas (mainly containingnitrogen, carbon dioxide, and water vapor), the effects of nitrogenoxide emission reduction and carbon negative emission can be optimal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural schematic diagram of a nitrogen oxide ultra-lowemission and carbon negative emission system in an embodiment of thepresent invention.

REFERENCE NUMERALS

Carbon negative emission system 1; biomass feed bin 11; dryer 12; firstinlet 121; second inlet 122; first outlet 123; first outlet pipeline1231; second outlet 124; pyrolysis coupling partial gasificationreaction furnace 13; reaction furnace body 131; reaction furnace shell132; inorganic carbon chamber 133; inorganic carbon emission port 134;pyrolysis agent/gasification agent air port 135; inorganic carbonconveying belt 136; first cyclone separator 14; nitrogen oxide ultra-lowemission system 2; boiler 21; first air supply mechanism 22; second airsupply mechanism 23; biomass stock bin 24; oxygen meter 25; secondcyclone separator 26; air supply device 3; air blower 31; induced draftfan 32; gas component analyzer 33; water vapor generator 34; combustionchamber 35; air blowing device 351; first pipeline 41; second pipeline42; third pipeline 43; fourth pipeline 44; flow monitoring meter 5;electric butterfly valves 6 a, 6 b, 6 c, 6 d.

DETAILED DESCRIPTION

The technical solutions in embodiments of the present invention will bedescribed clearly and fully hereinafter with reference to theaccompanying drawings in the embodiments of the present invention.Obviously, the embodiments described are only some, but not allembodiments of the present invention. Based on the embodiments in thepresent invention, all other embodiments obtained by a person ofordinary skill in the art without involving any inventive effort fallwithin the protection scope of the present invention.

First Embodiment

Please refer to FIG. 1 , the present invention provides a nitrogen oxideultra-low emission and carbon negative emission system, comprising: acarbon negative emission system 1, a nitrogen oxide ultra-low emissionsystem 2, an air supply device 3 and a flow control module (not markedin FIG. 1 ), wherein, the carbon negative emission system 1 is used forenabling biomass to have pyrolysis coupling partial gasification togenerate inorganic carbon and pyrolysis gas/gasification gas, and theinorganic carbon is used for returning to field treatment or makingcarbon-based materials such as activated carbon to realize negativeemission of carbon; the nitrogen oxide ultra-low emission system 2 isused for enabling fuel (including pure coal fuel, biomass fuel or mixedfuel of biomass and coal) to be in mixed combustion with the pyrolysisgas/gasification gas to remove nitrogen oxides generated by combustionof the fuel; the air supply device 3 is in communication with the carbonnegative emission system 1 via a first pipeline 41, and provides apyrolysis agent/gasification agent required for the biomass pyrolysiscoupling partial gasification, the air supply device 3 is incommunication with the carbon negative emission system 1 and thenitrogen oxide ultra-low emission system 2 via a second pipeline 42, andthe pyrolysis gas/gasification gas generated by the carbon negativeemission system 1 enters the nitrogen oxide ultra-low emission system 2via the second pipeline 42, and is in mixed combustion with the fuel inthe nitrogen oxide ultra-low emission system 2 to reduce the nitrogenoxide generated in the nitrogen oxide ultra-low emission system 2; theflow control module controls a flow ratio of a pyrolysisagent/gasification agent entering the carbon negative emission system 1and flow of the pyrolysis gas/gasification gas and air entering thenitrogen oxide ultra-low emission system 2.

Due to the above mode, the biomass generates the inorganic carbon andthe reductive biomass pyrolysis gas/gasification gas through pyrolysiscoupling partial gasification of the carbon negative emission system 1,the inorganic carbon can be used for returning to field treatment andsoil improvement, since the inorganic carbon is difficult to bedecomposed by soil microorganisms, this part of carbon can be sealed fora long time, and finally negative emission of carbon is achieved. Theinorganic carbon can also be used to make the carbon-based materialssuch as activated carbon adsorbents to adsorb harmful substances andaccumulate and store them to achieve negative emission of carbon; thereductive biomass pyrolysis gas/gasification gas co-fires withbiomass/coal solid fuel in the nitrogen oxide ultra-low emission system2, and the nitrogen oxides generated in the nitrogen oxide ultra-lowemission system 2 are converted into nitrogen that is harmless to theenvironment through complex chemical reactions, which realizes removalof the nitrogen oxide and achieves the purpose of ultra-low emission ofthe nitrogen oxide. The present invention regulates and controls theyield of the gasification gas/gasification gas and the component ratio,regulates and controls the yield of the inorganic carbon and realizesthe removal of the nitrogen oxide and the negative emission of carbon inthe process of biomass utilization by combining biomass pyrolysis,gasification and combustion, and controlling the flow ratio of thepyrolysis agent/gasification agent entering the carbon negative emissionsystem 1 and the flow of the gasification gas/gasification gas and airentering the nitrogen oxide ultra-low emission system 2.

In a preferential embodiment of the present invention, the carbonnegative emission system 1 comprises a biomass feed bin 11, a dryer 12,a pyrolysis coupling partial gasification reaction furnace 13 and afirst cyclone separator 14 which are sequentially in communication viapipelines. Specifically speaking, the biomass feed bin 11 providesbiomass fuel of a pyrolysis coupling gasification reaction; a firstinlet 121 of the dryer 12 is in communication with an outlet of thebiomass feed bin 11, so as to dry the biomass entering the dryer 12, asecond outlet 124 of the dryer 12 is in communication with the pyrolysiscoupling partial gasification reaction furnace 13, the dried biomassenters the pyrolysis coupling partial gasification reaction furnace 13via the second outlet 124 of the dryer to have a pyrolysis couplingpartial gasification reaction or a pure pyrolysis reaction, thepyrolysis coupling partial gasification reaction furnace 13 is used forenabling the biomass to have the pyrolysis coupling partial gasificationreaction to produce high-temperature pyrolysis gas/gasification gas andinorganic carbon, and the product after the biomass reaction enters thefirst cyclone separator 14 via an outlet of the pyrolysis couplingpartial gasification reaction furnace 13 to perform gas-solid separationto obtain fine inorganic carbon particles and the high-temperaturepyrolysis gas/gasification gas by the gas-solid separation. Preferably,an inlet of the first cyclone separator 14 is in communication with anoutlet in the side upper portion of the pyrolysis coupling partialgasification reaction furnace 13 so that the high temperature pyrolysisgas/gasification gas in the pyrolysis coupling partial gasificationreaction furnace 13 can sufficiently enter the first cyclone separator14.

In the embodiment of the present invention, drying the biomass beforepyrolysis/gasification of the biomass is beneficial to improve theefficiency of pyrolysis/gasification of the biomass, combustion productsare separated by the first cyclone separator 14, the reductive pyrolysisgas/gasification gas obtained by separation enters the nitrogen oxideultra-low emission system 2 to reduce the nitrogen oxide, and thecombustion products are separated, so that full recovery of theinorganic carbon can be promoted, at the same time the entry of fineinorganic carbon in the combustion products into the nitrogen oxideultra-low emission system 2 is reduced, and the negative emission ofcarbon is promoted.

In a preferential embodiment of the present invention, the pyrolysiscoupling partial gasification reaction furnace 13 comprises a reactionfurnace body 131, a reaction furnace shell 132, an inorganic carbonchamber 133, an inorganic carbon emission port 134 and a pyrolysisagent/gasification agent air port 135, the reaction furnace body 131 isdisposed inside the reaction furnace shell 132, a circulation space ofthe pyrolysis agent/gasification agent is formed between the reactionfurnace shell 132 and the reaction furnace body 131, the reactionfurnace shell 132 is in communication with an outlet of the firstpipeline 41, the inorganic carbon chamber 133 is disposed at the bottomof the pyrolysis coupling partial gasification reaction furnace 13, thebottom of the inorganic carbon chamber 133 is provided with theinorganic carbon emission port 134, and the pyrolysis agent/gasificationagent air port 135 is formed in the reaction furnace body 131, so as tocommunicate the reaction furnace shell 132 with the reaction furnacebody 131.

Specifically speaking, the reaction furnace body 131 is used as areaction site of the pyrolysis coupling partial gasification reaction ofthe biomass, the reaction furnace shell 132 is used for accommodatingand circulating the high-temperature pyrolysis agent/gasification agentto form a high-temperature cavity to provide heat needed for thepyrolysis coupling partial gasification reaction; the inorganic carbonchamber 133 is used for temporarily accommodating the inorganic carbonproduct, and the inorganic carbon emission port 134 is used fordischarging the inorganic carbon product which is later used forreturning to the field and making the carbon-based material; thepyrolysis agent/gasification agent air port 135 is used to provide aninlet for the high-temperature pyrolysis agent/gasification agent in thereaction furnace shell 132 to enter the reaction furnace body 131; andthe pyrolysis agent/gasification agent air port 135 is formed in thebottom of one side of the reaction furnace body 131. Further, in orderto facilitate the transportation of the inorganic carbon, an inorganiccarbon conveying belt 136 is further disposed at the bottom of theinorganic carbon emission port 134, and the inorganic carbon is conveyedin the form of the conveying belt for returning to the field treatmentor making the carbon-based materials such as activated carbonadsorbents, so as to realize the negative emission of carbon.

Due to the above mode, the reaction furnace shell 132 is incommunication with the outlet of the first pipeline 41, and thepyrolysis agent/gasification agent provided by the air supply deviceenters the reaction furnace shell 132 to provide gas and heat requiredfor the reaction furnace body 131, and the pyrolysis agent/gasificationagent in the reaction furnace shell 132 enters the reaction furnace body131 through the pyrolysis agent/gasification agent air port to enablethe biomass to have the pyrolysis coupling partial gasificationreaction. According to the different pyrolysis agents/gasificationagents, the pure pyrolysis reaction can also take place in the reactionfurnace body 131, for example, the pyrolysis agent/gasification agent isnitrogen, and the inorganic carbon in the combustion products generatedin the reaction furnace body 131 enters the inorganic carbon chamber andpasses through the inorganic carbon emission port to be discharged,which realizes recovery of the inorganic carbon. The inorganic carboncan be used for returning to field treatment and soil improvement. Sincethe inorganic carbon is difficult to be decomposed by the soilmicroorganisms, this part of carbon can be sealed for a long time, andfinally negative emission of carbon is achieved. The inorganic carboncan also be used to make the carbon-based materials such as activatedcarbon adsorbents, which can adsorb the harmful substances andaccumulate and store them to achieve negative emission of carbon.

In a preferable embodiment of the present invention, the nitrogen oxideultra-low emission system 2 comprises a boiler 21 and air supplymechanisms, the boiler 21 is used for combustion of the fuel (solidfuel) and the pyrolysis gas/gasification gas to achieve ultra-lowemission of the nitrogen oxide, the air supply mechanism provides gasrequired for the combustion of the fuel, and the boiler 21 is incommunication with a top outlet of the first cyclone separator 14through the second pipeline 42; an air outlet of the air supplymechanism is in communication with the interior of the boiler 21.

Due to the above mode, the fuel burns in the boiler 21 to supply heat tothe outside, and the high-temperature pyrolysis gas/gasification gaswith reducibility obtained by separation of the first cyclone separator14 enters the boiler 21 through the second pipeline 42 to reduce thenitrogen oxides in the boiler 21 to nitrogen, which achieves theultra-low emission of the nitrogen oxide.

Specifically, the boiler 21 is a circulating fluidized bed boiler, andthe air supply mechanisms comprise a first air supply mechanism 22 and asecond air supply mechanism 23, the first air supply mechanism 22 isdisposed at the bottom of the boiler 21, and the second air supplymechanism 23 is disposed corresponding to a combustion zone of thepyrolysis gas/gasification gas in the boiler 21. The first air supplymechanism 22 supplies the gas required for fuel combustion, the secondair supply mechanism 23 supplies the gas required for fuel combustion ina form of secondary air, the second air supply mechanism 23 is disposedat a position above the first air supply mechanism 22, and the boiler 21is provided with a secondary air port corresponding to the position ofthe second air supply mechanism 23. By additionally disposing thesecondary air port in the combustion zone of the biomass pyrolysisgas/gasification gas, on the premise that the total air supply volumeremains unchanged, the air volume of primary air is reduced, and reducedair is supplied into a hearth in the form of the secondary air. When theprimary air volume decreases, the combustion condition of biomass solidfuel in a dense phase zone will change, the nitrogen oxide is partiallyremoved in the dense phase zone, and the total removal efficiency of thenitrogen oxide is improved.

Further, a fuel feed bin 24 and an oxygen meter 25 are further includedin the boiler, the fuel feed bin 24 provides the fuel (includingbiomass/coal fuel) required for the combustion of the boiler 21, thenumber of the fuel feed bins is one or more, and the fuel feed bin 24 ispreferably disposed at a lower position of the boiler 21, so as toprovide the fuel for the lower portion of the boiler 21. The oxygenmeter 25 is disposed inside the boiler 21, preferably, the oxygen meter25 is disposed corresponding to the combustion zone of the pyrolysisgas/gasification gas in the boiler, and the oxygen meter 25 facilitatesregulating and controlling the emission of the nitrogen oxide accordingto an excess air coefficient by monitoring the content of oxygen in thecombustion zone of the biomass pyrolysis gas/gasification gas tocalculate the excess air coefficient.

Due to the above mode, the plurality of fuel feed bins 24 can providedifferent fuels respectively, the fuel can be pure biomass fuel or purecoal fuel, and can also be a mixture of the biomass fuel and the coalfuel; the two fuel feed bins 24 are disposed at the same height of theboiler 21; the two fuel feed bins 24 respectively supply the biomassfuel and the coal fuel, so as to realize mixed combustion of thebiomass/coal mixed-combustion solid fuel and the biomass pyrolysisgas/gasification gas, the content of a nitrogen element in the coal ishigher than that in the biomass, and therefore, compared with thebiomass fuel, the combustion of the coal fuel needs denitrificationtreatment more, so as to realize the ultra-low emission of the nitrogenoxides. A mixing ratio of biomass to coal can be determined according tothe actual supply amount of a power plant. The oxygen meter 26 ensuresthe ultra-low emission of the nitrogen oxide by monitoring the contentof the oxygen in the combustion zone of the pyrolysis gas/gasificationgas and the excess air coefficient, and adaptively adjusting the airsupply volume of the air supply mechanism.

Preferably, the nitrogen oxides ultra-low emission system 2 furthercomprises a second cyclone separator 26, the second cyclone separator 26is used for separating solid products and gaseous products ofcombustion, and specifically used for separating high temperature fluegas and unburnt solid particles. An inlet of the second cycloneseparator 26 is in communication with the upper portion of the boiler21, an outlet of the second cyclone separator 26 is in communicationwith the lower portion of the boiler 21, and the unburnt solid particlesseparated out by the second cyclone separator 26 enter the boiler 21through the lower portion of the boiler 21 to continue to burn.

In an optional embodiment of the present invention, the air supplydevice 3 comprises an air blower 31, an induced draught fan 32, a gascomponent analyzer 33 and a combustion chamber 35, the air blower 31provides the pyrolysis agent/gasification agent (nitrogen/air) requiredfor the carbon negative emission system 1, an outlet pipeline of the airblower 31 is in communication with the first pipeline 41, and theinduced draught fan 32 and the component analyzer 33 are disposed on thesecond pipeline 42 in a spaced mode; the second pipeline 42 communicatesthe first cyclone separator 14 with the boiler 21, the combustionchamber 35 is in communication with a second inlet 122 of the dryer 12via a third pipeline 43, so that heat is provided for the interior ofthe dryer 12 to dry the biomass, and the combustion chamber 35 iscommunicated between the induced draught fan 32 and the gas componentanalyzer 33 through a fourth pipeline 44; and the component analyzer 33is disposed between the boiler 21 and the induced draught fan 32 so asto facilitate analyzing the component content of the biomass pyrolysisgas/gasification gas entering the boiler 21.

The air supply device 3 further comprises a first outlet pipeline 1231connecting a first outlet of the dryer 12 with an inlet of the firstpipeline 41, and a water vapor generator 34. The combustion chamber 35is used for combustion of part of the pyrolysis gas/gasification gas,and high-temperature flue gas produced by combustion enters the dryer 12via the third pipeline 43 and provides heat for drying the biomass inthe dryer 12, and then the high-temperature flue gas is provided for thepyrolysis coupling partial gasification reaction furnace 13 via thefirst outlet pipeline 1231 and the first pipeline 41 together with watervapor precipitated in the drying process of the biomass fuel as apyrolysis agent/gasification agent; an outlet of the water vaporgenerator 34 is in communication with the inlet of the first pipeline41. Namely, the outlet pipeline of the air blower 31, an outlet pipelineof the water vapor generator 34, and the first outlet pipeline 1231 ofthe dryer 12 are collected at an inlet end of the first pipeline 41, anoutlet end of the first pipeline 41 is in communication with thereaction furnace shell 132 of the pyrolysis coupling partialgasification reaction furnace 13, and the water vapor generator 34, theair blower 31 and the combustion chamber 35 in communication with thefirst outlet 123 of the dryer 12 provide the pyrolysisagent/gasification agent required for the pyrolysis couplinggasification reaction; by controlling a flow ratio of the threepyrolysis agents/gasification agents from the air blower 31, the watervapor generator 34 and the combustion chamber 35, the yield of thepyrolysis gas/gasification gas and the component ratio can be regulatedand controlled, and the yield of the inorganic carbon can be regulatedand controlled.

Specifically, the air blower 31 is used for blowing air to provide thepyrolysis gas/gasification gas for the pyrolysis/pyrolysis couplingpartial gasification reaction; the induced draft fan 32 is used forintroducing the high-temperature pyrolysis gas/gasification gasgenerated in the pyrolysis coupling partial gasification reactionfurnace 13 into the subsequent boiler 21, and the induced draft fan 32is disposed to facilitate rapidly introducing the biomass pyrolysisgas/gasification gas separated by the first cyclone separator 14 intothe boiler 21; an inlet of the induced draft fan 32 is connected to anoutlet of the first cyclone separator 14, an outlet of the induced draftfan 32 is divided into two paths, one path is in communication with aninlet of the combustion chamber 35 via the fourth pipeline 44, a smallpart of the biomass pyrolysis gas/gasification gas enters the combustionchamber 35 for combustion, and a large part of the biomass pyrolysisgas/gasification gas is connected to an inlet of the gas componentanalyzer 33 via another path and enters the boiler 21 for reburning anddenitration. The gas component analyzer 33 is used to monitor thecomponent content of the biomass pyrolysis gas/gasification gas enteringthe boiler 21. The water vapor generator 34 is used to generate watervapor to provide the pyrolysis agent/gasification agent required forpyrolysis coupling partial gasification. An outlet of the combustionchamber 35 is in communication with a second inlet 122 of the dryer 12,the combustion chamber 35 is used for combustion of the small part ofthe biomass pyrolysis gas/gasification gas, the high-temperature fluegas generated by the combustion of the small part of the biomasspyrolysis gas/gasification gas enters the dryer 12, the high-temperatureflue gas enables water in the biomass fuel to be precipitated to formwater vapor, the high-temperature flue gas flows out through the firstoutlet 123 of the dryer 12 together with the water vapor, and thehigh-temperature flue gas generated by the combustion can also besupplied as the gasification agent to the reaction furnace body 131 fora partial gasification reaction to occur; an air blowing device 351 isconnected to the inlet of the combustion chamber 35 to supply airrequired for pyrolysis of the pyrolysis gas/gasification gas.

In a preferable embodiment of the present invention, flow monitoringmeters 5 are disposed on the outlet pipeline of the air blower 31, theoutlet pipeline of the water vapor generator 34, the first outletpipeline 1231 and the pipeline (outlet of the second pipeline 42)between the gas component analyzer 33 and the boiler 21, and used formonitoring flow of gas in each path in real time.

The outlet pipeline of the air blower 31 and the outlet pipeline of thewater vapor generator 34 are further provided with electric butterflyvalves 6 a and 6 b, and the flow control module controls the openingdegrees of the electric butterfly valves 6 a and 6 b so as to controlthe flow of the water vapor and the air. The fourth pipeline 44 and theoutlet of the second pipeline 42 (specifically, the pipeline locatedbetween the inlet of the gas component analyzer 33 and the outlet of thefourth pipeline 44) are provided with electric butterfly valves 6 c and6 d, and the flow control module controls the flow of thehigh-temperature pyrolysis gas/gasification gas entering the boiler 21and the flow of the flue gas entering the pyrolysis coupling partialgasification reaction furnace 13 by controlling the opening degree ofthe electric butterfly valves 6 c and 6 d. The flow control modulefurther controls the flow of air entering the boiler 21 and monitors thecontent of the oxygen in the combustion zone of the pyrolysisgas/gasification gas in conjunction with the oxygen meter 26.

In a preferred embodiment of the present invention, each connectingpipeline has a heat preservation function and is provided with atemperature monitoring device (not shown in the figures), wherein thetemperature on the pipeline of the induced draft fan 32 should becontrolled above 400° C. so as to prevent that high-temperature targenerated by pyrolysis/partial gasification condenses and blockagehappens.

According to the embodiment of the present invention, by this system,the removal efficiency of the nitrogen oxides can reach 80-90%, theremoval rate is high, and the ultra-low emission of the nitrogen oxideis achieved.

The structure of the nitrogen oxide ultra-low emission and carbonnegative emission system of the present invention is specificallydescribed above, and a control method and a specific working flowthereof are described below.

The control method comprises:

when biomass in a carbon negative emission system 1 has a pyrolysiscoupling partial gasification reaction, opening electric butterflyvalves 6 a, 6 b, 6 c and 6 d on an outlet pipeline of an air blower 31,an outlet pipeline of a water vapor generator 34, a fourth pipeline 44and an outlet of a second pipeline 42; the air blower 31 blowing in air;and

adjusting a flow ratio of water vapor entering the carbon negativeemission system 1, air and high-temperature fuel gas generated in acombustion chamber 35 together with water vapor precipitated whenbiomass fuel is dried by controlling the opening degrees of the electricbutterfly valves 6 a, 6 b, and 6 c, thereby adjusting a component ratioof pyrolysis gas/gasification gas, the yield of the pyrolysisgas/gasification gas and the yield of inorganic carbon.

Furthermore, the method further comprises: controlling temperature in aboiler 21 (for example, performing adjustment according to thetemperature of the boiler reflected by a temperature sensor), an excessair coefficient of a combustion zone of the pyrolysis gas/gasificationgas in the boiler 21, a total excess air coefficient in the boiler 21,and a distribution ratio of the air supply volumes of a first air supplymechanism 22 and a second air supply mechanism 23 (controlling a ratioof the first air supply volume and the second air supply volume bydisposing the electric butterfly valves on outlet pipelines of the firstair supply mechanism 22 and the second air supply mechanism 23) so as toachieve ultra-low emission of nitrogen oxides.

A work process includes: the biomass fuel is fed into a dryer 12 via thebiomass feed bin 11 for drying and dewatering, heat required for dryingis provided by the high-temperature flue gas generated by partialbiomass pyrolysis gas/gasification gas combusted in the combustionchamber 35 in an air supply system 3, and the biomass after being driedand dewatered is sent out of an outlet of the dryer 12, falls into anupper feed port of a pyrolysis coupling partial gasification reactionfurnace 13 (introduced by taking a fixed bed reaction furnace as anexample, the same below) and enters the pyrolysis coupling partialgasification reaction furnace 13, falls down under the action ofgravity, and makes contact with a pyrolysis agent/gasification agent inthe falling process to have a pyrolysis coupling partial gasificationreaction. In the upper portion of the pyrolysis coupling partialgasification reaction furnace 13, a pyrolysis reaction mainly occurs,and volatiles of the biomass are heated and precipitated to producereductive pyrolysis gas such as CO, H₂, CH₄ and C_(n)H_(m), with thefalling of the biomass, a partial gasification reaction occurs to theinorganic carbon to produce reductive gasification gas such as CO, H₂,CO₂, CH₄ and C_(n)H_(m), and a content ratio of the gasification gasproduct is related to a ratio of gasification agents from differentsources. The inorganic carbon after partial gasification falls into afurnace bar (not shown in the FIGURE) at the bottom of the pyrolysiscoupling partial gasification reaction furnace 13, and enters aninorganic carbon chamber 133 via the furnace bar, and falls onto aninorganic carbon conveying belt 136 via an inorganic carbon emissionport 134, and the biomass after the pyrolysis coupling partialgasification reaction is converted into inorganic carbon to be subjectedto returning to field treatment; this part of inorganic carbon isdifficult to be decomposed by soil microorganisms, and this part ofcarbon is just from CO₂ in air fixed by photosynthesis during the growthperiod of the biomass, thus achieving long-term sealing of this part ofcarbon in soil, namely, achieving negative emission of carbon; at thesame time, the inorganic carbon products can also be used to makecarbon-based materials, such as activated carbon adsorbents to adsorbharmful substances and then accumulate and store them, so as to realizethe negative emission of carbon, thereby greatly reducing the emissionof carbon dioxide.

The gasification agent required for the partial gasification reactionconsists of a mixture of gas from three different sources, including:water vapor generated by the water vapor generator 34, air introduced bythe air blower 31 and the high-temperature flue gas generated by thepartial biomass pyrolysis gas/gasification gas combusted in thecombustion chamber 35, and the water vapor precipitated during thedrying process of biomass together with them; the gasification agentsfrom the three sources are combined and enter a circulating spacebetween a reaction furnace shell 132 and a reaction furnace body 131.

When the water vapor is used as the gasification agent, the gasificationproducts are mostly H₂, CO, CH₄ and C_(n)H_(m), and a promotion effectof the water vapor on the formation of H₂ is most obvious. When the airis used as the gasification agent, the gasification products are mostlyCO and CO₂, when an air content increases, the content of CO willdecrease and the content of CO2 will increase; when the gasificationagent is the high-temperature flue gas (mainly comprising CO₂ and N₂)generated by partial biomass pyrolysis gas/gasification gas combustion,the gasification product is mostly CO generated by reacting CO2 withcoke; the gasification products can be regulated and controlled byregulating and controlling the flow of the gasification agents fromdifferent sources according to the demand for the content ratio of thegasification gas products. The gasification agents from the threesources are combined and enter the reaction furnace shell 132 together,and the high-temperature flue gas provided by the combustion chamber 35contains a large amount of heat, so that the reaction hearth shell 132forms a high-temperature cavity, which can provide heat required for thepyrolysis reaction and the partial gasification reaction occurring inthe reaction furnace body 131; and the gasification agent in thehigh-temperature cavity enters the reaction furnace body 131 through apyrolysis agent/gasification agent air port 135 under the action ofpressure, and participates in the pyrolysis coupling partialgasification reaction of the biomass. The pyrolysis gas/gasification gasgenerated after the biomass has the pyrolysis coupling partialgasification reaction enters a first cyclone separator 14 together withfine inorganic carbon particles, after the inorganic carbon particlesare separated by the first cyclone separator 14, the pyrolysisgas/gasification gas is sent to a subsequent system via an induced draftfan 33, and the separated fine inorganic carbon particles fall onto theinorganic carbon conveying belt 16 via the inorganic carbon emissionport 134, and are then subjected to returning to field treatment or madeinto the carbon-based materials such as activated carbon adsorbents;after flowing out of an outlet of the induced draft fan 32, thehigh-temperature pyrolysis gas/gasification gas is divided into twopaths, a small part of the pyrolysis gas/gasification gas enters theabove-mentioned combustion chamber 35 for a combustion reaction, thecontents of CO, CO₂, H₂, CH₄, C_(n)H_(m), H₂O and other gas in the otherpart of the pyrolysis gas/gasification gas are monitored via the gascomponent analyzer 33, then the pyrolysis gas/gasification gas entersthe boiler 21 for reburning, and the flow of the two paths of gas can becontrolled according to the opening degrees of the electric butterflyvalves 6 c and 6 d disposed on the fourth pipeline 44 and the secondpipeline 42.

In the boiler 21, the biomass solid fuel is fed into a dense phase zoneof the boiler through a feed bin 24 for combustion, and air required forcombustion is supplied by the air blower 31 and enters a hearth from thebottom of the hearth of the boiler 21 through an air distribution plate(not shown in the figures). Preferably, a part of the air can beintroduced in the form of secondary air, that is, supplied in throughthe second air supply mechanism 23. The nitrogen oxides produced by thecombustion of the biomass solid fuel meet the reductive high-temperaturebiomass pyrolysis gas/gasification gas which is fed into the hearth asreburning gas during the upward movement, and in the reburning processof this part of reductive pyrolysis gas/gasification gas, a large amountof nitrogen oxides are reduced to nitrogen which is harmless to air, sothat the ultra-low emission of the nitrogen oxides is achieved. H₂,C_(n)H_(m) and CO mainly play a reduction role, and the processmechanism of the specific reduction reaction is as follows:

1. H₂ Reduction

H2→2H′  (1)

H+NO→HNO′  (2)

HNO′+H→NH′+OH′  (3)

NH′+NO→N₂+OH′  (4)

NH′+NO→N₂O+H, N₂O+H→N₂+OH′  (5)

NH′+NO₂→N₂O+OH′, N₂O+H→N₂+OH′  (6)

H₂+NO_(x)→N₂+H₂O(total)  (7)

2. C_(n)H_(m) Reduction

C_(n)H_(m))→CH₂′/CH₃′+H′  (8)

CH₂′+NO→HCNO+H′, CH₂′+NO→HCN+OH′  (9)

CH₃′+NO→H₂CN′+OH′, CH₃+NO→HCN+H₂O  (10)

HCN+O′→NH′+CO  (11)

HCNO+O′→NH′+CO₂  (12)

H₂CN+O′→NH′+CO+2H₂O  (13)

NH′+NO→N₂+OH′  (4)

NH′+NO→N₂O+H, N₂O+H→N₂+OH′  (5)

NH′+NO₂→N₂O+OH′, N₂O+H→N₂+OH′  (6)

C_(n)H_(m)+O′→H′+HCCO′  (14)

HCCO′+NO→HCNO+CO  (15)

HCCO′+NO→HCN+CO₂  (16)

HCN+O′→NH′+CO  (11)

HCNO+O′→NH′+CO₂  (12)

NH′+NO→N₂+OH′  (4)

NH′+NO→N₂O+H, N₂O+H→N₂+OH′  (5)

NH′+NO₂→N₂O+OH′, N₂O+H→N₂+OH′  (6)

C_(n)H_(m)+NO_(x)→N₂+CO₂+H₂O(total)  (13)

3. CO Reduction

NO+NO→ON═NO(NO dimer)  (17)

CO+ON=NO→CO₂+N₂O  (18)

CO+N₂O→CO₂+N₂  (19)

2CO+2NO→2CO₂+N₂(total)  (20)

CH₄, H2, and CO are three components that play a major role in thereduction process of the nitrogen oxides since CH₄ is the main componentgas in C_(n)H_(m). It can be seen from the reaction formula,

reducibility of H₂ is mainly reflected in the reduction of NO_(x) by theintermediate product NH′, NO_(x) can be directly reduced by NH′ to N₂(as shown in equation (4)), and can also be reduced by NH′ to N₂O, andthen the N₂O is reduced by H′ radicals to N₂ (such as equations (5) and(6));

Reduction of NO_(x) by CH₄ is mainly reflected in reduction of NO_(x) bythe intermediate product CH₂′/CH₃′, and also includes reduction of NO bythe intermediate product HCCO′, and a final conversion step to N₂ issimilar to H₂ reduction; reduction of NO_(x) by CO is mainly reflectedin reduction of NO by CO, and it goes through the intermediate productof NO dimer and is finally reduced to N₂. Among three reducing agents(CH₄, H₂ and CO), the removal efficiency of the nitrogen oxides by CH₄and H₂ is higher than that by CO, therefore, the content of CH₄ and H₂in the gasified gas should be increased as much as possible to realizethe ultra-low emission of the nitrogen oxide.

The three gasification agents from different sources: increasing theproportion of the water vapor gasification agent will increase thecontent of H₂ in the gasification product, but will reduce the contentof CO and CH₄, and will also reduce the heating value of thegasification gas;

increasing the proportion of the air gasification agent will increasethe content of CO and CH₄ in the gasification product and the heatingvalue of the gasification gas, but will decrease the content of H₂;

increasing the content of flue gas (N₂ and CO₂ being main components)produced by combustion of a small part of the gasification gas and watervapor together with it will increase the content of CO in thegasification product, reduce the reducibility of the gasificationproduct, and also cannot greatly increase the heating value of thegasification gas, so the main function of this part of gas is to provideheat for the pyrolysis coupling partial gasification reaction in theabove-mentioned implementation process, and the content of thehigh-temperature flue gas as the gasification agent should be reduced asfar as possible under the condition of ensuring sufficient heat.

In conclusion, the content of the water vapor gasification agent and theair gasification agent should be reasonably controlled, so that thegasification product of pyrolysis coupling partial gasification has bothextremely high nitrogen removal efficiency and high heating value forfuel, so that the energy is fully utilized, and the amount of thishigh-temperature flue gas gasification agent should be controlled as lowas possible, but should meet the heat required for thepyrolysis/gasification reaction. When the content of H₂, CH₄ and CO inthe gasification product is 10-15%, 5-10% and 25-30%, the gasificationgas has extremely high removal efficiency on the nitrogen oxides andhigh heating value at the same time, so that the energy is fullyutilized and the goal of ultra-low emission of the nitrogen oxide isachieved.

In addition to the component ratio of the gasification agents fromvarious sources in the pyrolysis gas/gasification gas, temperature ofthe hearth, the excess air coefficient in the combustion zone of thebiomass pyrolysis gas/gasification gas, the water content of the fueland the air volume ratio between primary and secondary air supply areall factors to be considered in achieving the ultra-low emission of thenitrogen oxides. As the temperature increases, the NO_(x) reductionefficiency by biomass pyrolysis gas/gasification gas reburning willincrease, but the NO_(x) formation efficiency will also increase whenthe fuel burns in the dense phase zone, and the hearth temperature ofthe boiler 21 should be controlled to be 850-950° C. to reduce thenitrogen oxide formation efficiency in the dense phase zone and improvethe nitrogen oxide removal efficiency in a reduction zone. Preferably,an additional heating device may be added to the combustion zone of thebiomass pyrolysis gas/gasification gas to control the temperature of thelocal zone to be 1100-1200° C. to improve the reduction efficiency ofthe pyrolysis gas/gasification gas for the nitrogen oxides.

The excess air coefficient of the combustion zone of the biomasspyrolysis gas/gasification gas is also a key factor affecting theremoval efficiency of the nitrogen oxide. Only by ensuring that the zoneis in a fuel-rich combustion condition (excess air coefficient lessthan 1) can the nitrogen oxides be removed with high efficiency. The airsupply amount of the air supply mechanism should be adjusted accordingto the feeding amount of the biomass solid fuel and the gas feeding flowof the biomass pyrolysis gas/gasification gas, the total excess aircoefficient is controlled to be 1.2-1.6, and the excess air coefficientof the combustion zone of the biomass pyrolysis gas/gasification gas iscontrolled to be 0.7-0.8 by adjusting the flow of the biomass pyrolysisgas/gasification gas (adjusting the flow of the pyrolysisgas/gasification gas entering the combustion zone of the boiler 21 bycontrolling the opening degree of the electric butterfly valve 6 d), soas to avoid the oxidation of the intermediate product NH′ to NO_(x) byexcess O₂, and ensure the ultra-low emission of the nitrogen oxides.Preferably, the oxygen meter 26 can be added to the combustion zone ofthe biomass pyrolysis gas/gasification gas to monitor the excess aircoefficient of the zone in real time and performs regulation andcontrol.

Preferably, the air volume of the primary air is reduced while keepingthe total air supply amount unchanged, and the reduced air is suppliedto the hearth in the form of secondary air. When the amount of theprimary air decreases, the combustion condition of the biomass solidfuel in the dense phase zone of the boiler 21 changes, the amount of NH′oxidized to NO decreases, and NO reacts with non-oxidized NH′ togenerate N₂, so that the nitrogen oxides are partially removed in thedense phase zone. The excess air coefficient in the dense phase zoneshould be controlled to be 0.8-0.9, in which case the NO generated bythe oxidation of NH′ just right reacts with NH′ to generate N₂, and theremaining NO_(x) is generated basically by the oxidation of HCN, so asto reduce the pressure for removing the nitrogen oxide borne by thecombustion zone of the biomass pyrolysis gas/gasification gas andimprove the total removal efficiency of the nitrogen oxide.

The water content of the biomass solid fuel also affects the removalefficiency of the nitrogen oxide. If the water content of the biomasssolid fuel is high, the volatile precipitating process is retarded toslow down, the retention time of volatiles in the dense phase zone isshortened, and a combustion section moves upward as a whole. At thistime, the primary air volume should be appropriately reduced and thesecondary air volume should be appropriately increased, otherwise alarge amount of NO would be generated in the dense phase zone.

In summary, to achieve ultra-low emission of the nitrogen oxide, thefactors to be regulated and controlled are the component ratio and flowof the biomass pyrolysis gas/gasification gas (regulated and controlledby the flow ratio of three pyrolysis agents/gasification agents), thehearth temperature, the excess air coefficient of the combustion zone ofthe pyrolysis gas/gasification gas, the total excess air coefficient,the primary and secondary air volume ratio of the air supply mechanismand the water content of the biomass solid fuel.

Second Embodiment

In the second embodiment of the present invention, a pyrolysis couplingpartial gasification reaction of biomass takes place in a pyrolysiscoupling partial gasification reaction furnace 13 (taking a fixed bedreaction furnace as an example), and if the biomass only has a pyrolysisreaction in an inert gas environment without a partial gasificationreaction, the content of reductive gas in a gas product, especially thecontent of H₂ and CO, will be greatly decreased, but the content ofinorganic carbon is increased to some extent. If pyrolysis gas with alow H₂ and CO content can still achieve high nitrogen removalefficiency, it can be controlled that only the pyrolysis reaction takesplace in the pyrolysis coupling partial gasification reaction furnace13, so as to improve the yield of the inorganic carbon while ensuringthe high nitrogen removal efficiency, and achieve negative emission ofcarbon to a greater degree.

In this embodiment, an electric butterfly valve 6 b on an outletpipeline of a water vapor generator 34, and an electric butterfly valve6 c on a fourth pipeline 44 are closed, and electric butterfly valves 6a and 6 d on an outlet pipeline of an air blower 31 and a secondpipeline 42 are opened, air supply of the air blower 31 is changed tonitrogen supply, and nitrogen is blown into the pyrolysis couplingpartial gasification reaction furnace 13 by the air blower 31, so thatthe biomass has a pure pyrolysis reaction under a nitrogen atmosphere.The subsequent processes are the same and will not be described againhere.

The above are only preferable embodiments of the present invention andare not intended to limit the present invention. Any modifications,equivalent replacements, improvements, etc. made within the spirit andprinciples of the present invention shall be included in the protectionscope of the present invention.

1. A nitrogen oxide ultra-low emission and carbon negative emissionsystem, comprising: a carbon negative emission system, a nitrogen oxideultra-low emission system, an air supply device and a flow controlmodule, wherein: the carbon negative emission system is configured toproduce a pyrolysis coupling partial gasification reaction of a biomassor produce a pure pyrolysis reaction of the biomass to generateinorganic carbon and pyrolysis gas/gasification gas; the inorganiccarbon being usable for returning to field treatment or makingcarbon-based materials to realize negative emission of carbon; thenitrogen oxide ultra-low emission system is configured to mix combustionof fuel with the pyrolysis gas/gasification gas to remove nitrogenoxides generated by combustion of the fuel; the air supply device is incommunication with the carbon negative emission system via a firstpipeline, and provides a pyrolysis agent/gasification agent required forbiomass pyrolysis coupling partial gasification, the air supply deviceis in communication with the carbon negative emission system and thenitrogen oxide ultra-low emission system via a second pipeline, and thepyrolysis gas/gasification gas enters the nitrogen oxide ultra-lowemission system via the second pipeline, and is in mixed combustion withthe fuel in the nitrogen oxide ultra-low emission system to reduce andremove the nitrogen oxide; the flow control module controls a flow ratioof the pyrolysis agent/gasification agent entering the carbon negativeemission system and flow of the pyrolysis gas/gasification gas and airentering the nitrogen oxide ultra-low emission system.
 2. The nitrogenoxide ultra-low emission and carbon negative emission system accordingto claim 1, wherein the carbon negative emission system comprises adryer, a pyrolysis coupling partial gasification reaction furnace and afirst cyclone separator which are sequentially in communication viapipelines, the dryer dries the biomass provided, the dried biomassenters the pyrolysis coupling partial gasification reaction furnace viaa second outlet of the dryer to have the pyrolysis coupling partialgasification reaction or the pure pyrolysis reaction, and the productafter the reaction of the biomass enters the first cyclone separator viaan outlet of the pyrolysis coupling partial gasification reactionfurnace to perform gas-solid separation
 3. The nitrogen oxide ultra-lowemission and carbon negative emission system according to claim 2,wherein the pyrolysis coupling partial gasification reaction furnacecomprises a reaction furnace body, a reaction furnace shell, aninorganic carbon chamber, an inorganic carbon emission port and apyrolysis agent/gasification agent air port, the reaction furnace bodyis disposed inside the reaction furnace shell, a circulation space ofthe pyrolysis agent/gasification agent is formed between the reactionfurnace shell and the reaction furnace body, the reaction furnace shellis in communication with an outlet of the first pipeline, the inorganiccarbon chamber is disposed at a bottom of the pyrolysis coupling partialgasification reaction furnace, a bottom of the inorganic carbon chamberis provided with the inorganic carbon emission port, and the pyrolysisagent/gasification agent air port is formed in the reaction furnacebody.
 4. The nitrogen oxide ultra-low emission and carbon negativeemission system according to claim 3, wherein the nitrogen oxideultra-low emission system comprises a boiler and air supply mechanisms,the boiler is configured to combust the fuel and the pyrolysisgas/gasification gas, the air supply mechanisms are configured toprovide gas required for combustion of the fuel through communicationwith the boiler, and the boiler is in communication with a top outlet ofthe first cyclone separator through the second pipeline.
 5. The nitrogenoxide ultra-low emission and carbon negative emission system accordingto claim 4, wherein the air supply mechanisms comprise a first airsupply mechanism and a second air supply mechanism, the first air supplymechanism is disposed at a bottom of the boiler, and the second airsupply mechanism is disposed corresponding to a combustion zone of thepyrolysis gas/gasification gas in the boiler.
 6. The nitrogen oxideultra-low emission and carbon negative emission system according toclaim 5, wherein the nitrogen oxide ultra-low emission system furthercomprises at least one fuel feed bin and an oxygen meter, each the fuelfeed bin provides the fuel required for combustion of the boiler, theoxygen meter is disposed corresponding to the combustion zone of thepyrolysis gas/gasification gas in the boiler, and the oxygen meter isconfigured to monitor the content of oxygen in the combustion zone ofthe pyrolysis gas/gasification gas in the boiler.
 7. The nitrogen oxideultra-low emission and carbon negative emission system according toclaim 6, wherein the air supply device comprises an air blower and acombustion chamber, an outlet pipeline of the air blower is incommunication with an inlet of the first pipeline, the air blowerprovides the pyrolysis agent/gasification agent required for the carbonnegative emission system, the pyrolysis agent/gasification agentcomprises nitrogen or air, the combustion chamber is in communicationwith a second inlet of the dryer via a third pipeline, the combustionchamber is configured to combust part of the pyrolysis gas/gasificationgas, and the combustion chamber is in communication with a middle partof the second pipeline via a fourth pipeline, and the first cycloneseparator is in communication with the boiler via the second pipeline;flue gas generated by combustion in the combustion chamber enters thedryer through the third pipeline and provides heat for drying thebiomass in the dryer, and after drying, this part of flue gas enters thefirst pipeline together with water vapor precipitated in the dryingprocess of biomass fuel.
 8. The nitrogen oxide ultra-low emission andcarbon negative emission system according to claim 7, further comprisingan induced draft fan and a gas component analyzer, the induced draft fanbeing disposed at an inlet of the second pipeline, and the gas componentanalyzer being disposed at an outlet of the second pipeline.
 9. Thenitrogen oxide ultra-low emission and carbon negative emission systemaccording to claim 8, wherein the air supply device further comprises afirst outlet pipeline and a water vapor generator, and the inlet of thefirst pipeline is in communication with a first outlet of the dryer viathe first outlet pipeline; the flue gas generated by combustion in thecombustion chamber is provided for the pyrolysis coupling partialgasification reaction furnace via the first outlet pipeline togetherwith the water vapor precipitated when drying the biomass fuel as thepyrolysis agent/gasification agent; an outlet pipeline of the watervapor generator is in communication with the inlet of the firstpipeline, and the water vapor generator provides the pyrolysisagent/gasification agent required for the pyrolysis coupling partialgasification reaction furnace.
 10. The nitrogen oxide ultra-low emissionand carbon negative emission system according to claim 9, furthercomprising a plurality of flow monitoring meters and a plurality ofelectric butterfly valves, the plurality of flow monitoring meters arerespectively disposed on the outlet pipeline of the air blower, theoutlet pipeline of the water vapor generator, the first outlet pipelineand the outlet of the second pipeline; the plurality of electricbutterfly valves comprise a first electric butterfly valve disposed onthe outlet pipeline of the air blower, a second electric butterfly valvedisposed on the outlet pipeline of the water vapor generator, a thirdelectric butterfly valve disposed on the fourth pipeline, and a fourthelectric butterfly valve disposed on the outlet of the second pipeline.11. A control method of the nitrogen oxide ultra-low emission and carbonnegative emission system according to claim 10, comprising the followingsteps: when biomass in the carbon negative emission system has a purepyrolysis reaction, closing the second electric butterfly valve and thethird electric butterfly valve; opening the first electric butterflyvalve and introducing nitrogen, and opening the fourth electricbutterfly valve; or when the biomass in the carbon negative emissionsystem has a pyrolysis coupling partial gasification reaction, openingthe first electric butterfly valve, the second electric butterfly valve,the third electric butterfly valve and the fourth electric butterflyvalve, the air blower blowing in air; adjusting a flow ratio of watervapor entering the carbon negative emission system, air and fuel gasgenerated in the combustion chamber together with water vaporprecipitated when biomass fuel is dried by controlling the openingdegrees of the first electric butterfly valve, the second electricbutterfly valve and the third electric butterfly valve, therebyadjusting a component ratio of pyrolysis gas/gasification gas, the yieldof the pyrolysis gas/gasification gas and the yield of inorganic carbon.12. The control method of the nitrogen oxide ultra-low emission andcarbon negative emission system according to claim 11, furthercomprising controlling temperature of the boiler, an excess aircoefficient of the combustion zone of the pyrolysis gas/gasification gasin the boiler, a total excess air coefficient in the boiler, and adistribution ratio of air supply volumes of the first air supplymechanism and the second air supply mechanism to realize nitrogen oxideultra-low emission.
 13. A control method for controlling an apparatuscomprising a carbon negative emission system, a nitrogen oxide ultra-lowemission system, an air supply device and a flow control module, the airsupply device being is in communication with the carbon negativeemission system via a first pipeline and being in communication with thecarbon negative emission system and the nitrogen oxide ultra-lowemission system via a second pipeline, wherein the control methodcomprises: producing, with the carbon negative emission system, apyrolysis coupling partial gasification reaction of a biomass orproducing a pure pyrolysis reaction of the biomass to generate inorganiccarbon and pyrolysis gas/gasification gas; the inorganic carbon beingusable for returning to field treatment or making carbon-based materialsto realize negative emission of carbon; mixing, with the nitrogen oxideultra-low emission system, combustion of fuel with the pyrolysisgas/gasification gas to remove nitrogen oxides generated by combustionof the fuel; providing, with the air supply device a pyrolysisagent/gasification agent required for biomass pyrolysis coupling partialgasification, the pyrolysis gas/gasification gas entering the nitrogenoxide ultra-low emission system via the second pipeline, and mixingcombustion with the fuel in the nitrogen oxide ultra-low emission systemto reduce and remove the nitrogen oxide; and controlling, with the flowcontrol module, a flow ratio of the pyrolysis agent/gasification agententering the carbon negative emission system and flow of the pyrolysisgas/gasification gas and air entering the nitrogen oxide ultra-lowemission system.